1. Field of the Invention
The present invention relates to a diaphragm control apparatus of an interchangeable lens camera.
2. Description of the Related Art
In the related art (Japanese Unexamined Patent Publication No. 2011-28241), a diaphragm control apparatus of interchangeable lens camera is disclosed, which is provided with an interchangeable lens having a diaphragm device, which varies the aperture of a diaphragm between a maximum aperture (i.e. fully-open state) and a minimum aperture (i.e. fully stopped-down state). The camera body of the interchangeable lens camera is provided with a drive motor, which drives the diaphragm device in opening/closing directions in a lens-mounted state.
The interchangeable lens is provided with a diaphragm operatively-associated rod, which moves the diaphragm device between maximum and minimum apertures, and the camera body is provided with a diaphragm control projection which moves, in association with the diaphragm operatively-associated rod, between lower and upper extremities (which correspond to the maximum and minimum apertures of the diaphragm device, respectively) of the diaphragm device. The diaphragm control projection is biased by a biasing spring of the camera body towards the lower extremity, which corresponds to the fully-open state of the diaphragm device.
With this structure, during a photographing stand-by state in which the interchangeable lens has been mounted on the camera body (or immediately after the interchangeable lens is mounted on the camera body), the diaphragm control projection is positioned at the lower extremity because of the biasing force of the biasing spring on the camera body side, thus the fully-open state of the diaphragm device is maintained by the diaphragm operatively-associated rod on the interchangeable lens side.
However, the related art has the following two problems.
Firstly, when the power switch of camera body is in an OFF state, the diaphragm device maintains the fully-open state, and sunlight can enter into the camera body from this opening of the diaphragm device, and thereby damage some of the camera components (such as the image sensor burning out or components made of resin material melting).
Secondly, the total number of camera parts/components increases due to a biasing spring inside the camera body for biasing diaphragm control projection, and due to other parts for supporting the biasing spring, thereby complicating the structure inside the camera body.